Right, so I use the GIMP typically.
Unfortunately, I've hit a bit of a plateau. I've reached a point where I need the power of Photoshop to accomplish what I want.

Every once in a while I hit a brick wall when I try to do something though.

Here's one of them:

I'm attempting to convert a greyscale image into a mask to be used for another layer. My issue? I can't figure out how.
In the GIMP, I just select the greyscale layer, copy it, then select the mask and paste the B&W into the mask. *Poof!* Instant mask.

I'm running into issues doing that here. Any suggestions?

Thanks in advance!

Good question, never thought about having to do that before but it would make an interesting image for sure. Hopefully someone here more experienced can figure it out

Wow shanomoo. I use it ALL the time when I chop. I'm looking at your entries and I'm amazed you've never used it before. It's incredibly useful.
I refuse to believe there isn't a way to do this in Photoshop.

So... More experienced choppers: What Next?

1. go to the layer with the image you want to use as a mask, turn off the other layers
press Ctrl-Atl-~ to make a selection based on the composite (everything visible) channel



alternatively you can use Ctrl-Alt-1 to make a selection based on the red channel, Ctrl-Alt-2 (green), etc. Note: Explore the Channels palette, it is your friend for making complex masks

2. With the selection still on (marching ants) turn off the 'mask source' layer, go to the layer you want to apply the mask to and...



3. click the mask button at the bottom of the Layers palette



Note about masks: black is opaque (image does not show), white is transparent, grayscale is all in between, etc, etc.

Alternatively (as there are so many ways to skin the cat in Photoshop):
- open both images
- go to the image you want to apply the mask to
- go to Select - Load Selection
- the source will be your grayscale document, click OK (this will make the selection)
- click the mask button at the bottom of the Layers palette

Alright! That makes sense. So clicking the "Add Mask" button while having a selection will generate a new mask based on it. Fantastic. I've got one more question for you. (Since you know so much)
In GIMP, you can use a "Color to alpha" feature which (You guessed it) turns a given color transparent. Here's my second question.
Is there a feature like this in Photoshop AND is it possible to use an IMAGE as a "Color to alpha" Template. (Where the blue overlaps, it turns transparent, where the green overlaps it turns transparent, ETC.)
Thanks in advance for your help vokaris!

There is no built-in feature to match the 'Color-to-Alpha' filter in GIMP. You can go to Select - Color Range - use the pick tool (explore the options to add or remove colors from the selection) and the fuzziness slider, click OK to make your selection and create a mask

Crap. That's my second favorite tool. Thanks anyways. I might just use GIMP for that feature alone in the future. Thanks again for your help!